Ion exchange compositions are well known and include molecular sieves, clays, and non-porous inorganic oxides. These compositions are typically synthesized as powders and formed into shaped articles, such as beads, extrudates, pellets, pills, and the like, in order to be commercially useful. When formed into its final shape, the articles must possess sufficient physical strength to withstand abrasion or attrition and fracture during use, loading and transit.
In forming such shaped articles a binder or matrix material is often used, which can provide strength yet will not interfere with the properties of the ion exchange composition. Commonly used matrix materials or binders include aluminas and clays since these materials can be mixed easily with the ion exchange compositions and can be formed into shaped articles easily by using techniques such as extrusion. However, the extrusion processing necessary to form sufficiently strong shaped articles using alumina and clay binders is performed at temperatures that cause deactivation of certain ion exchange compositions. In order to avoid high temperature processing, liquid solutions of zirconium or titanium salts have been used to bind the ion exchange composition with zirconium or titanium oxides.
Thus, typical processes for forming shaped articles include forming a single ion exchange composition, typically highly active toward a desired ion species, with a zirconium or titanium binder. Generally, the shaped articles are primarily formed from the active ion exchange composition, such as with an ion exchange composition content of over 50 weight percent (wt %). Such shaped articles typically have a binder content of less than 50 wt %. These parameters provide little flexibility in tuning the ion uptake capacity of shaped articles.
Accordingly, it is desirable to provide improved shaped articles and improved methods for forming shaped articles. Further, it is desirable to provide shaped articles and methods for forming shaped articles with tunable ion uptake capacity. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.